94,129
edits
Changes
no edit summary
|genus=Fallopia
|genus=Fallopia
|species=japonica
|species=japonica
|common_name=Japanese knotweed
|habit=shrub
|habit=shrub
|habit_ref=Flora - A Gardener's Encyclopedia ISBN 0881925381
|habit_ref=Flora - A Gardener's Encyclopedia ISBN 0881925381
|usda_ref=Flora - A Gardener's Encyclopedia ISBN 0881925381
|usda_ref=Flora - A Gardener's Encyclopedia ISBN 0881925381
|max_zone=8
|max_zone=8
|image=Upload.png
|image=Fallopia japonica MdE 2.jpg
|image_width=240
|image_width=240
|image_caption=Japanese Knotweed
}}
}}
'''Japanese Knotweed''' (''Fallopia japonica'', [[synonymy|syn.]] ''Polygonum cuspidatum'', ''Reynoutria japonica'') is a large, [[herbaceous]] [[perennial plant]], native to eastern [[Asia]] in [[Japan]], [[China]] and [[Korea]]. In North America and Europe the species is very successful and has been classified as [[invasive species|invasive]] in several countries.
A member of the family [[Polygonaceae]], Japanese knotweed has hollow stems with distinct raised [[node (botany)|node]]s that give it the appearance of [[bamboo]], though it is not closely related. While stems may reach a maximum height of 3–4 m each growing season, it is typical to see much smaller plants in places where they sprout through cracks in the pavement or are repeatedly cut down. The [[leaf|leaves]] are broad oval with a truncated base, 7–14 cm long and 5–12 cm broad, with an entire margin. The [[flower]]s are small, cream or white, produced in erect [[raceme]]s 6–15 cm long in late summer and early autumn.
Closely related species include giant knotweed (''[[Fallopia sachalinensis]]'', syn. ''Polygonum sachalinense'') and Russian vine (''Fallopia baldschuanica'', syn. ''Polygonum aubertii'', ''Polygonum baldschuanicum'').
Other English names for Japanese knotweed include fleeceflower, Himalayan fleece vine, monkeyweed, Hancock's curse, elephant ears, pea shooters, donkey rhubarb (although it is not a [[rhubarb]]), sally rhubarb, Japanese bamboo, American bamboo, and Mexican bamboo (though it is not a [[bamboo]]). There are also regional names, and it is sometimes confused with [[sorrel]].
==Cultivation==
==Cultivation==
===Invasiveness===
In the U.S. and Europe, Japanese knotweed is widely considered an [[invasive species]] or [[weed]].<ref>[http://www.invasive.org/eastern/biocontrol/12Knotweed.html Biological control of invasive plants in the Eastern United States]</ref> It is listed by the [[World Conservation Union]] as one of the [[List of the world's 100 worst invasive species |world's 100 worst invasive species]].<ref>[http://www.issg.org/database/species/search.asp?st=100ss IUCN Global Invasive Species Database]</ref>
The invasive root system and strong growth can damage foundations, buildings, flood defences, roads, paving, retaining walls and architectural sites. It can also reduce the capacity of channels in flood defences to carry water.<ref>[http://www.gardenroots.co.uk/content.php?8-Japanese-knotweed-costs Article on the costs of Japanese Knotweed]</ref>
The most effective spraying solution contains about 5%-10% [[glyphosate]] in water. (To make a 5% solution from a 40% concentrate mix 1 part concentrate with 7 parts water.) Ready-to-use solutions that contain less than 5% glyphosate are too weak and do not work. A small amount of liquid dish-washing detergent can be added to improve wetting of the leaves. If possible, both sides of the leaves should be sprayed until they are completely wet. It takes about 3 weeks for most of the plants to die. After 3 weeks, all remaining plants should be sprayed again. This process needs to be repeated until all the plants die. The US federal government will come and spray Japanese knotweed for no charge in many areas under the Invasive Species Act. Local county extension agencies can be contacted for more details.
===Propagation===
===Propagation===